Dual oil burner control system



May 5, 1936. J. P. KRIECHBAUM DUAL OIL BURNER CONTROL SYSTEM Filed Oct.16, 1933 JOHN P. KRIECHBAUM' Patented May 5, 1936 UNITED STATES PATENTOFFICE DUAL OIL BURNER CONTROL SYSTEM John P. Krlechbaum, Minneapolis,Minn.

Application October 16, 1933, Serial No 693,756 7 Olaims. (01.158-28)The present inventlon relates to the art of automatically burning fuelsparticularly for the heating of homes and the heating of water to beused therein for domestic purposes.

One of the objects of the present invention i's the provision of meansfor controlling the supply cf fue1 to any one of a, plurality of burnersand simultaneously supplying combustion supporting air t at least thoseburners which are in operation, together with means rendt'ered operativeupon operation cf any' one of the burners for maintaim'ng the supply ofcombustion supporting air for a, period after cessation of operation ofall cf said burners.

More particularly, the means for maintalnlng the supply 0\f combustionsupporting air to the burners comprisias a thermostatic switchingmechanism responsive to the temperature of combustion produced by any orall of the burners and which includes a, switch which opens upon a fallin temperature Whereby the supply of combustion air is malntained untilthe temperature of combustion -falls ab least a predetermined amount a.sa result"of cessaion o'f operation of all of said burners.

A further. object of the invention 15 the provision of two or moreheaters f or heating different devices, objects er mediums and means forcoutrolling the supply 0f fuel to each of the burners in accordance Withchanges in the ccmditions produced er controlled by the burners andsimultaneously supplying combustion supporting alr thereto together withauxiliary means rendered operative upon operation of any one o:t' thebumers for maintaining the supply o& combustion supporting air for aperiod after cessation of operatiofi of all oftheburners.

A further objectof the invention is the provislon of two er more heatingdevices which are all connected to a common stack for the passage of thegases of combustion f1 um the various bumers and means respcnsive toconditions produced by operation of the burners for controlling thesupply of fuel a.nd cqmbustion supportlng air thereto, together withmeans responsive to the temperature cf the gaseS of combustion passingthrough the common stack for the various bumersfor maintaim'ng thesupply of combustion supporting air to at least those burners which arein operation for a period after the c8ssation of combustion of the lastof the burners to be in operation. Sr cifically, one of the heatingdevices is utilized to heat a space or dwelling and the other' of theheating devices heats a supply 0I hol: water Ior use in thespac e ordwelling heated by the other of the heating devices. Also, preferably,the control system is completely electrical and the means responsive tothetemperature cf the gases in the common stack is a combustiontemperature responsive switch which is operated upon temperaturereversals and o:pens when the tempera-. ture of the .combustion gasespassing through the stack has decreased at least a.- predeterminedamount.

Another object of the invention is the provision 10 of a simpleinexpensive control system by means 0f which the supply of fuel 130 ahea.ter is varied or stopped or started in accordance with the beatingdemands but in which the supply of combustion supporting air isinitiated when the heater is placed in operation and is prolonged fo1 a.period after the supply of fuel is decreased or shut oif.

Other objects will be found in the following detalled descripticm, theaccompanying drawing and the appended claims.

Referring to the single fig'ure of the drawings, a. heating devicegenerally indicated at I0 for heating a space such as a dwelling isherein shown as eomprising the usual warm air furnace,

but lt is to be understood that any other wellknown type cf heatingapparatus could be utilized in its place. The warm air furnace I0 isDrovided with the usua1 combustion chamber II ahd an air heating chamberI2. The frnace I0 is herein illustrated as being heated by a liquid fuelburner generally indlcated at I3 which comprises a circular combustionpot I4, located within the combustion chamber II and. .adapted 150receive a supply 015 liquid fuel from a, pipe I5 which is controlled byan electric valve I6 of any wellknown constructlon.

The furnace I0 is provided with a fan I'I for producing a clrculation 0fair through the 2.11

heating chamber I2, 0 1i; headers I8 and to the 40 room or spa.ce to belieated. The fan I'I is herein shown as located in the cold .LiI intakeI9 of the furnace I0 and is adapted po be driven by an electric motbr20. v

A the1mostatlc switching mechanism'iesponsive to the temperature of theair in the a.ir heating chamber I2 is generally indicated. ab 2I andcomprises a casing 22, a tubular extension 23 by means of which theswitching mechanism is' ser ranged that II; is normally closed, as shownin the drawing and on1y opens when the temperature of the air in airheating chamber I2 becomes excessive and will hereinafter be referred toas the high limit switch. The switch 21 is so airanged that it opens andremains open whenever the temperature of the air inair heating cha.mberI2 is at or below some predetermined minimum value say, 150 F. and willhereinafter be referred to as the fan switch. Such switching mechanismsare well-known in the art and need no further detailed explanation.

A water heater is herein shown as a furnace 30 within which is located aliquid fuel burner having a circular combustion pot 3I adapted toreceive a supply of liquid fuel from .a pipe 32 which is controlled byan electrioally operated valve 33 of any of the usual constructions.Wlthin the heater 30 'is located a pipe coil 34, the upper end of whichcommumcates with the upper end of a water storage tank 35 and the lowerend 015 which communicates with the lower end the1eof. The water storagetank 35 is provided with an in1et pipe 36 by means of which the tank 35and pipe coil 34 are provided with a supply of cold water as needed. Thestorage tank 35 is further provided with a hob water outlet pipe 31which may be connected to the domestic bot water supply pipes in theusual manner. A thermostatic switch, generally indicated at 38, isquite'similar in construction to the switching mechanism 2I in that II:oomprises a casing 39 havin'g atubular extension 40 by which the casing39 is secured. 1:0 the water tank 35, a helically coiled thermostatloelement 4l located within the tank 35 and having one of its ends securedto extension 40, and a torsion rod 42 which extends into and terminates'within casing 39 am]. is seeured to the other end of thermostaticelement 4I. Within the casing 39 and operated by torsion rod 42 Is amercury switch 43 of well-known construction, the mercnry switch 43being so arranged that II. closes a circuit when the temperature of thewater in the water tank 35 is at or below some predetern'iined. minimumtemperature say 160'-F;

A common stank 45 is connected to the combustion chamber of the warm airfurnace I by means of a pipe 46 and is connected to the combustionchamber of the w'ater heater 30 by means of a. pipe 4I. Associated withthe common stack 45 is a draft concrolling device herein shown as adraft fan 48 located within the common stack 45 and. driven by anelectric motor 49. Also associated with the common stack 45 is athermostatic switching mechanism generally indica.ted at 50 whichcomprises a casing I, a, tubular extension 52, a, helically coiledthermostatic element 53, and a torsion rod 54. One end of thermostaticelement 53 is secured to tubular extension 52 and the other end thereofIs secured 130 torsion rod 54. The torsion rod 54 terminates withincasing 5I and is conneeted to a. mercury switch 55 located therein bythe usual welI-known neu-positive transmission means o1 slip frictionconnection whereby the mercury switch 55 Is operated upon temper'aturereversals rather than at predetermined temperature values in a. mannerwellknown in the .art. The mercunf switch 55 is so Iplaced and the usualstop mechanism associated 12herewith in such manner that the mercuryjsfoialenswhenthe temperature of the gases in the 'cic xnin'onstack 45lowers a1; least a predetermined .afi'mlint The switch 55 will behereinafter refer:e d to as the Stack switch.

An oil supply pipe 60 is oonnected to the In1et of valve I6 by means ofa pipe 6I and Is likewise connected to the inlet of valve 33 by a pipe62. Ignition means fozthe burner I3 is herein shown as comprising aby-pass pipe 63 having a needle valve 64, therein, the by-pass pipebeing connected to pipes 6I and I5 so as to s hunt valve I6 and theneedle va1ve 64 being so adjusted that there is always a relativelysmall flow of oil to the combustion pot I4 whereby a small pilot flameis maintained at all times. In a similar man ner, a by,-pass pipe 65which is p'rovided with a needle valve 66 connects pipes 62 and 32whereby a small supply of oilis constantly fed to combustlon pot 3I 0fwater heater 30 so as I:o maintain a small pilot flame at all times. II:is to be understood that this oil pilot type of ignltion means has beenshown herein as merely exemplary of one type of ignition means and thatany of the other wellknown types of ignition means could be utillzed ifdesired.

The control system includes a room thermstat which is hereindiagrammatically indicated as comprising a. mercury switch 68 whichclosed a circuit when the temperature of the room or space to be heatedfalls to some predetermined minimum, say '70 F. The control mechanismalso includes a relay generally indicated at 69 which relay comprises arelay coil I0, an armature II, a switch arm I2, and a. coope'ratingcontact I3. The arrangement is such that upon energlzation ofrelay 0011I0 the armature II is attracted and moves switch arm 12 into engagementwith conta.ct I3 and upon deenergization of relay coil I0, armature IImoves to the positi0n shown In the drawings under the influence cfgravity whereby switch arm I2 is movedaway from coutact I3. A slmllarrelay generally indicated at. 14 is also included in I;he control systemand comprises a relay coil I5, an armature I6, a switch arm IIcontrolled thereby, and a cooperating oontact I8. In thisparticularembodiment of the invention, the control system is also sho'wnas including a manual switching mechanism I9 which indudes a. manuallyoperable switch am 80 which normally engages a contact button III butmay be moved into engagement with a couta.ct button 82. Power issupplied by line wires 83 a.nd 84 which may include the usual manuallyoperated line switch 85.

Operation With the parts in the position shown, the space or roomtemperature is above the desired polnt; inasmuch as room therm0statswitch 68 Is shown in its open position and the water temperature 35 isat or above the desired point inasmuoh as mercury switch 43 is also inopen position. Oil valves I6 and 33 are therefore both clos'ed am] thefurnace I0 and water heater 30 are inoperative except for thehereinbefore mentioned small pilot flame which is herein shown for thepurpose cf ignition. The temperatur6 of the gases in the stack 45 hasdropped since the last operation o1. either of the heaters with theresult that stack switch 55 is in open position. Likewise, thetemperature of the air in air heating chamber I2 has droppedconsiderably since the last operation of the furnace I0 so that highlimit swit'ch 26 is closed and fan switch 21 is open. Fan motor 20 anddraft motor 49 are both inoperative and relay coils and I5 aredeenergized.

The temperature of I;he room dr space t;o ba heated will, after a.period, drop below the desired value whereupon room thermostat switch 08will niove 130 closed circuit position. =Movement cf room thermostatswitch 68 to closed circuit positlon establishes a circuit for.oil valveI6, a circuit for relay coil I and conditions a. circuit for fan motor20. The oil valve circult ls as follows: line 83, wire 80, roomthermostat switch 68, wire 9I, high limit switch 26, wire 92, wire 93,oil valve I6, wire 94, wire 95, and wire 96 to line 84. The energizingcircuit f0r relay 10 is as follows: line 83, wire 80, room thermostatswitch 68, wire 9I, high limit switch 26, wire 92, wire 91, relay coilI0, and wire 98 to line 84. Energization of relay coil I0 moves switcharm I2 into engagement with conta.ct 13 to establish the following draftmotor circu it: line 83, wire 99, contact I3, switch arm I2, wire IOI,wire I02, wlre I03, draft moto'r 48, and wlre I04 to line 84.

Energizatlon of oil valve I6 opens the same whereupon a full flow of oilis fed from oil supply pipe 60 through pipe 6I, oil valve I6, and pipe It o combustion pot I4. This full flow of oil is ignited by the sn'1allpilot flame already burning in the combust ion pot I4 Whereupon thefurnace I0 ls placed in condition to heat the air in air heating chamberI2. Energization of draft m0- tor 49 operates draft fan 48 130 create a.draft in the common stack 45 whereby a draft through furnace I0 andwater heater 30 is created. Initial operation of furnace I0 createsan-increase in I:he temperature of the gases passing through ccmmonstack 45 with the result that stack switch 55 quickly moves to closedcircuit position to establish a maintaining circuit for draft motor 49as follows: line 83, Wire I08, stack switch 55, wire I09, wire I02, wireI03, draft motor 49 and wire I04 to line 84.

After the furnace I0 has been in operation for a short tlme, the air inair heatlng chamber I2 will become heated sufficiently'to causethermostatic element 24 150 close fan switch 21 Whereupon fan motor 20ls energized by the following circuit: line 83, wire 90, room thermostatswitch 68, wire 9I, fan switch 21, wire I05, contact button 8I, manuallyoperable switch arm 80, wire I06, fan motor 20, wire I0'I, nd wire 96 toline 84. Operation of fan motor 20 drlves fan I I whereupon air iscirculated through air heating chamber I2 and headers I8 to the rooms orspace to be heated.

As long a.s the room temperature remains below the desired point, oilvalve I6 Will remaln open un1ess the temperature of the hea.ted air inthe air heating chamber I2 rises above the setting of limlt switch 26whereupon the llmit switch 26 will move to open circuil; position anddeenergize oil valve I6 until such time as the temperature of the a.lrin air chamber I2 decreases to 1:0 a point below the setting of the'limit switch 26. Opening 01 hlgh limit switch 26 also deenergizes relaycoil whereupon the initial energizing circuit f or draft motor 49 lsopened but the draft; motor 49 will continue in operation for at least ashort time until the temperature 0f the stack gases fallssufiiciently toopen stack switch 55. Likewise, fan motor 20 will continue in operatlonas long as room thermostat switch 68 is clased unless the temperature013 the air in a.ir chamber I2 falls blow the setting of the fan switch21.

Wh en the room temperature has been restored room thermostat switch 68opens, oil valve I6' lay;coil I0, a.nd fan m0tor 20 will all be deenzed.-l A s abdve pointed out however, draft r'nofoi 49 will bemaintained en'erg-ized by stack 'swlt'ch 55 for a shc rt period untilthe temperature of the gases passing through common stack 45 has droppedat least; a predetermined amount. 'I'his delayed deenergization ofdraftmotor 49 is provided for the usual purpose of furnishing combustionsupporting air to combustion pot I4 for a short period after closure ofvalve I6 whereby the relatively la.rge amount of oil present incombustion pot I4 at the time oil valve I6 closes is supplie d witlsufilcient combustion supporting alt to provide proper smokelesscombustion. By the time draft motor 49 is deenergized as the result ofopening of stack switch 55, the quantity of oil in combustion pot I4will have been reduced to the amount of oil permitted to flow throughneedle valve 64 in by-"pass pipe 63. Sufiicient air for sup'bortingcombustion of this sma.ll amount of oil is provided by the natural draftin the system.

In the similar manner, the temperature of the water in storage tank 35will fall below the desired point whereupon mercury switch 43 Will beclosed to establish energizing circuits for oil vlve 33 and relay coilI5. The circuit for oil valve 33 is as follows: line 83, wire IIO,switch 43, wire III, wire II2, oil valve 33, wire H3, wire 95, and wire96 130 line 84. The energizing circuit for relay coil I5 is as folows:line 83, wire IIO, switch 43, wire lll wire H4, relay coil I5, and wireIl5 to line 84. Energization of oil valve 33 permlts a full flow of oilto combustion pot 3I ancl energization cf relaycoil 15 moves switch armI'I into engagement with contact I8 1:0 establish the followingenergizing circuit for draft motor 49: line 83, wire H6, contact I6,switch arm 'II, w1're II'I, Wire I03 draft motor 49 and wire I04 to line84. Operation of draft motor 49 produce s a. draft through common stack45 and through furnace I0 and water heater as hereinbefore brought out.Combustion cf the large flow of oil to combustion pot 3I- first servesto raise the temperature of the stack gases whereupon stack switch 55'closes 150 establish I:he above mentioned maintaining circuit for draftmotor 49. This combustion 01 oil in combustion pot 3I also heats pipecoil 34 whereby the water in storage tank 35 ls heated until thetemperature of the same returns to the desired point at which timeswitch 43 opens to deenergize 'oil valve 33 and relay coil I5.Deenergiaztion of relay coil 15 interrupts the initlal energizingcircuit for draft motor 48 but; the maintaining circuit therefor will bemaintained until the stack gas temperature has dropped at least apredetermined amount to open stack switch 55 whereby combustlonsupporting air ls furnished combustion pot 3I until the excess oiltherein has been consumed in the manner previously pointed out inconnection with thecombustion of the oil in co-mbustlon pot I4.

Manually operable switch 19 may be utilized in order to operate fanmotor 20 and fan I I for ventilating purposes by m0ving manuallyoperable switch arm. 80 from contact button 8I and into engagement Wlthcontact button 82 to complete an energizing circuit for fan motor 20 asfollows: line 83, wlre II8, contact button 82, manually operable switcharm 80, wire I06, fan motor 20, wire I0I, and wire 96 t0 line 84.

From the fo regcing description, it will be noted that the presentinvention provides a simple improved cont'rol system by means of whichthe supply of combustion supporting air for a burner may be maintainedfor a. periud after thecessation of combustion. II: Will also be rlotedthat the invention provides a simple control system for a, plurality ofburners which are herein shown as each burner is controlled in responseto changes in difierent eonclitions. Spiacifically, one of the bu1nersis for the purpose of heating a dwelling er space and the other is forthe purpose of supplylng hot water. The burnersare connected to a commonstack ar'1d the invention utillzes a single draft controlling device,the arrangement being such tha.t when either burner is operated a supplyof combustion supporting air is furnished thereto and this supplyofCombustion supporting air is maintained by means of a, single deviceresponsive to the temperature of the gases passing through the commonstack for a timed period after closure of the last to close of thevalves-to wit, for a timed period after cessatyion v of combustion atthe burner last to be shut down.

It is t be understood that any of the usual safety devices may beprovided inconnection with the two burners for preventing operationthereof in the event the pilot flame falls or combustion fails to beestablished.

A specific embodiment of the invention has been herein shown anddescribed but lt will be apprecialted that many changes and modifica;-tions can be made by those skilled in the a1t and I am therefore t'o belimited only in the purview of the appendecl claims.

I claim:

1. In combination, a pair of heetters each having a burner and a fuelsupplying means therefor, a stack common to said two heaters, aneleotrical draft producing means operative to produce a draft throu'ghsaid common stack and heaters when energized an electrically 0p'eratedfuel.sup ply valve in each of said fuel supplying means, t"1ermostaticmeans responsive to temperature conditions produced by said heaters,energizing circults operative to energize said fuel valves to open thesame and- 1:0 energize said draft producing means controlled by saidthermostatic means, switching means responsive to the temperature of thegases passing through said common stack and including a switch whichcloses after combustion is obtained in elther of said heaters and openswhen the temperature of'the gases passing A through the common stackfalls a predetermined amount alter cessation of combustion in both ofsaid heaters, and a circuit operative to maintain operation of saiddraft producing means comtrolled only hy said switching means.

2. In cornbination, a pair of heaters each havlng a burner and a fuelfeeding means therefor a common stack Ior said two heaters, a draft fanfor prbducing a draft through said common stack, an electrie motor fordrlving said fan, an electrical fuel valve in each of said fuel feedingmeans which opens when energized and closes when dee"fierglzed athermostatic switch responslve to a temperatur'e}- condition produced byone of said heaters andwhich closes when the value of said conditlondecreases to a predetermined value, a relay, a clrcult for said relayand. one of said fuel valves Controlled by said thermostatic switch; a v

second thermostatic switch, parallel energizing clrcults 1'0r said draftfan motor controlled by said relays a switch responsive to thetemperature of the gases passlng through said common Stack whlch closesalter combustion is obtained and which opens when the Stack gastemperature falls a. predetermlned. amount after oessation ofcombustion, and a third circultfor said draft fan motor controlled onlyby said stack gas temperature responsive switch.

3. In combination; a. heater for heating a. space arid having a burnerand a. fuel supplying means therefor; a water heater havlng a burner anda fuel supplylng means therefor; a. common stack f0r said two heaters;a. draft controlling device in control of the draft through said commonstack; a space heater fuel supply valve; a water heate't fuel supplyvalve; a space temperature responslve thermostat; connections betweensaid space temperature responsive thermostat, space heater fuelsupplyvalve, and draft controllirlg device operative to open said valveand to operate said device when the space temperature falls to apredetermined minimum; a water temperature responsive thermostat;connections between said walzer'temperature responsive thermostat, waterheater fuel supply valve and draft controlling device operative to opensaid valve and to operate said device when the water temperature fallsto a predetermined minimurn; and. a Single device operative to maintainoperation of said draft con: trolling device for a time period afterclosure of the last to close of said fuel supply valves.

4. In combinatlon; a. heater for a space to' be' heated having a burnerand fuel feeding means therefor; a water heater having a burner and.fuel feeding means therefor; 9. common stank for said two heaters; anelectrlcally Operated draft riroducing device which creat9s a draftthrough said common stack when energized; an electrically operatecl fuelvalve in each of said fuel feedlng means; a, space temperatureresponsive thermostatic switch; circuit connectlons between said switch,space heater fuel valve, and draft producing device operative to opensaid valve and energlze said device when the space temperature falls toa predetermined minimum; a water temperature responslve thermostatlcswitch; electrlcal connections between said water temperature responslvethermostatic switch, water heater fuel valve, and draft producing deviceoperative to each of said burners, control means operative toselectively open-said valves, a single ineans in control of the drattfor all of said. burners counections associated Wlth said controlniearis and valves arranged to operate said draft controlling means toincrease the drait to all of said burners upon the opening of any one ofsaid valves by the control means, a slngle stank for all of saidburners, a single device res'ponsive to the temperature of eombustion insaid stack produced by operation of any of said burners, and connectionsbetvireen said device and draft controlllng means arranged to operatethe latter to c ontinue the increased draft to all of said burners,until the temperature of combustion in said stack has decreased at leasta predetermlned amount as a Cil result 0f cessation of operatlon 01 all01 sa1d burners.

6. In comblnatlon, a plurality of hea.ting de'vices each including a.burner, a, separate fuel supply controlllng vallve controlling thesupplying cf fue1 to each of said burners, a. thermostat responsive toa. heat condition produced by one of said burners operative to bpen 1tsfuel supply valve when said heat condition reaches a, predeterminedminimum, a thermostat responsive to a heat candltion produced by anotherof said burners operative to open its fuel supply valve when seidlastmentioned hea.t condition decreases to a predetermined minimum,means 111 control of the draft for all of sa.id burners, connectionsbetween said thermostats and draft controlling means operative toincrease the draufi; to all of said burners when fuel is supplied to anyone of said burners, a. common stack for all 013 seid heating devices, asingle device responsive to the temperature of combustion in sald stack,and connections' between said device and draft; controlllng meansoperative to maintain such increased dratt to all of said bumers untilthe temperature of combustion has decreased at least a predeterm.lnedamount upon cessation of combustlon ab all o1 said burners.

7. In combination, a, plurality of heating devices each having a burnerand a. fuel supply therei'or, a. separate fuel valve in control of theflow o! Iuel to ea.ch of said burners, a singlemeans in control of thedraft fdr all of sa.id burners, control mea.ns, means includingconnections between sa1d control means and valves and seid single draftcontrol means operative selectively 170 open seid valves and to operaixasaid draft controlling means upon the opening 1 any one of seid. valves,and a. Single device operative t;o maintain operation of said draftcontrolling means for a, periofl after closure of the last to;closeofsaig1 fue1 valves.

JOHN P. KRIECHBAUM.

